/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.ComponentModel;
using System.Configuration;
using System.Globalization;
using System.Xml;

namespace Spring.Core.TypeConversion;

/// <summary>
/// Custom <see cref="System.ComponentModel.TypeConverter"/> implementation for
/// <see cref="System.Collections.Specialized.NameValueCollection"/> objects.
/// </summary>
/// <remarks>
/// <p>
/// Handles conversion from an <b>XML formatted string</b> to a
/// <see cref="System.Collections.Specialized.NameValueCollection"/> object
/// (see below for an example of the expected XML format).
/// </p>
/// <p>
/// This converter must be registered before it will be available. Standard
/// converters in this namespace are automatically registered by the
/// <see cref="Spring.Objects.ObjectWrapper"/> class.
/// </p>
/// </remarks>
/// <example>
/// <p>
/// Find below some examples of the XML formatted strings that this
/// converter will sucessfully convert. Note that the name of the top level
/// (document) element is quite arbitrary... it is only the content that
/// matters (and which must be in the format
/// <c>&lt;add key="..." value="..."/&gt;</c>. For your continued sanity
/// though, you may wish to standardize on the top level name of
/// <c>'dictionary'</c> (although you are of course free to not do so).
/// </p>
/// <code escaped="true">
/// <dictionary>
///		<add key="host" value="localhost"/>
///		<add key="port" value="8080"/>
/// </dictionary>
/// </code>
/// <p>
/// The following example uses a different top level (document) element
/// name, but is equivalent to the first example.
/// </p>
/// <code escaped="true">
/// <web-configuration-parameters>
///		<add key="host" value="localhost"/>
///		<add key="port" value="8080"/>
/// </web-configuration-parameters>
/// </code>
/// </example>
/// <author>Rod Johnson</author>
/// <author>Juergen Hoeller</author>
/// <author>Simon White (.NET)</author>
public class NameValueConverter : TypeConverter
{
    /// <summary>
    /// Creates a new instance of the
    /// <see cref="Spring.Core.TypeConversion.NameValueConverter"/> class.
    /// </summary>
    public NameValueConverter()
    {
    }

    /// <summary>
    /// Returns whether this converter can convert an object of one
    /// <see cref="System.Type"/> to a
    /// <see cref="System.Collections.Specialized.NameValueCollection"/>
    /// </summary>
    /// <remarks>
    /// <p>
    /// Currently only supports conversion from an
    /// <b>XML formatted</b> <see cref="System.String"/> instance.
    /// </p>
    /// </remarks>
    /// <param name="context">
    /// A <see cref="System.ComponentModel.ITypeDescriptorContext"/>
    /// that provides a format context.
    /// </param>
    /// <param name="sourceType">
    /// A <see cref="System.Type"/> that represents the
    /// <see cref="System.Type"/> you want to convert from.
    /// </param>
    /// <returns>True if the conversion is possible.</returns>
    public override bool CanConvertFrom(
        ITypeDescriptorContext context,
        Type sourceType)
    {
        if (sourceType == typeof(string))
        {
            return true;
        }

        return base.CanConvertFrom(context, sourceType);
    }

    /// <summary>
    /// Convert from a string value to a
    /// <see cref="System.Collections.Specialized.NameValueCollection"/> instance.
    /// </summary>
    /// <param name="context">
    /// A <see cref="System.ComponentModel.ITypeDescriptorContext"/>
    /// that provides a format context.
    /// </param>
    /// <param name="culture">
    /// The <see cref="System.Globalization.CultureInfo"/> to use
    /// as the current culture.
    /// </param>
    /// <param name="value">
    /// The value that is to be converted.
    /// </param>
    /// <returns>
    /// A <see cref="System.Collections.Specialized.NameValueCollection"/>
    /// if successful.
    /// </returns>
    public override object ConvertFrom(
        ITypeDescriptorContext context,
        CultureInfo culture, object value)
    {
        string text = value as string;
        if (text != null)
        {
            XmlDocument doc = new XmlDocument();
            doc.LoadXml(text);
            return new NameValueSectionHandler()
                .Create(null, null, doc.DocumentElement);
        }

        return base.ConvertFrom(context, culture, value);
    }
}
